Starting means for free piston motor compressors



g- 1939- R. PATERAS PESCARA 2,168,828

STARTING MEANS FOR FREE PISTON MOTOR COMPRESSORS Filed July 11, 1936 2 Sheets-Sheet l Patented Aug 8, 1939 UNITED STATES STARTING MEAN S "FOR- FREE PISTON MOTOR CODIPRESSORS Raul Pateras Pescara, Paris, France, assignor to Socit dEtudes et de Participations, Eau, Gaz; Electricite, Energie, S. A., Geneva, Switzerland Application July 11, 1936, Serial No. 90,237 In Belgium July 15, 1935 21 Claims.

This invention relates to internal-combustion motor-compressor units of the free and opposed piston type and more particularly to starting and stabilizing means applicableto said devices; and

it relates still more particularly to improvements in certain starting and stabilizing means disclosed in my co-pending application Ser. No. 707,595, which means consisted, namely, in pneumatic energy storing means or accumulators whose mean up and transition period lasting until said motor-compressor has reached its normal operating regime, than the mean pressure under which said energy storing means co-operate with the sta biliz ing means in normal operation.

My above-mentioned co-pending application related mainly to engines of the type in question provided with energy storing means ,or' accumulators operating under substantially constant pressure during at least part of the stroke of the reciprocating piston assemblies.

The main purpose of myinvention is'to make said means also applicable to motor-compressors of the type in question provided with energy storing means in which the 'pressure'is more or less variable during all or part of the stroke of the reciprocating piston assemblies, while their construction and operation are simplified.

The principal object of my invention is to provide, in an internal-combustion motor-compressor unit of the free and opposed piston type, energy storing stabilizing means adapted to propel the motive pistons during the initial starting up period, and adapted, during the subsequent warming up period, and 'until the motor-compressor unit has reached its normal operating regime, to function under mean efiectiv'e pressures substantially higher than those required in said stabilizing means in normal operation, and means for progressively reducing said mean effective pressures in said stabilizing means, as the pressure in the compressed gas storage reservoir increases, said pressure-reducing means being adapted to reduce the amount of air in said stabilizing means gradually as the .total energy. available .for the return stroke exceeds allowable limits.

Another object is to provide, in a motor-compressor of the type described, means forreducing the mean pressure in said stabilizing means during the warming up period, by connecting same to the suction of one of the pressure stages or of the auxiliary starting compressor.

A further object is to provide, in a motor-compressor of the type described, means for reducing the mean pressure in said stabilizing means durefiective pressure was higher during the starting ing the warming up period adapted to release air from said stabilizing means whenever the return stroke of the pistons exceeds the normal inner dead center. x

A still further object is to provide, in a motor E compressor of the type described, energy-storing stabilizing means, and means for compensating the leakage of compressed fluid from said stabilizing means, by placing the same, ateach stroke, in communication with a source of fluid under l pressure,-for example with the high-pressure delivery either. directly or through the medium of a pressure reducing valve.

A still further object is to provide, in a motor compressor of the type described, means for permanently applying the suction pressure of pressure stages higher than the first to the inactive or rear faces of the compressor pistons in said stages, for the purpose of effecting, after the shut down of the unit, the return of the pistons to 20 their outer dead centers;

A still further object is to provide, in a motor compressor of the type described, pneumatic means for instantly and automatically returning the motive pistons to their outer dead centers, 5 after the shut down ofthe unit.

Other objects and advantages of my invention will appear to one skilled in the art from the following description with reference to the accompanying drawings, which description and 30 drawings are, of course, given by way of illustration, and should not be construed as limiting the scope of the invention.

In these drawings:

Fig. 1 illustrates diagrammatically a two-stage 35 free piston motor-compressor unit embodying my invention.

Figs.- 2 and 3 illustrate two variants of the same.

In one of the] preferred embodiments of my 40 invention concerning more particularly a twostage free-piston motor-compressor unit, as illustrated in Fig. 1, two oppositely reciprocating mo- I tive pistons l and I are rigidly connected to compressor-pistons 2 and 2 and to auxiliary45 cushioning pistons 3 and 3 thus forming two oppositely reciprocating piston assemblies co-.acting withthree groups of co-axial cylinders, namely a single motor cylinder 4, two compressor cylinders 5 and 5 and two pneumaticenergy 5o storing cylinders or accumulators 6 and 6 In the case of motor-compressors comprising sev-. eral compression stages as illustrated in Fig. 1, which refersmore particularly to the vertical type, I prefer to dispose said compression stages iii compressor 20 may advantageously be synchronized with that of the main motive pistons, for example by means of kinematic linkages such as 30 the suction and delivery phases of said auxiliary compressor being suitably timed.

The same linkages may also be adapted to operate other accessories, such as the fuel injection pump 3 l for example by disposing said linkages so as to exert a sudden thrust on the plunger '32 of the fuel pump, when the motive pistons are at or near their inner dead center.

The motor-compressor may be shut down by stopping the fuel injection, for example, by providing said fuel pump plunger 32 with a piston 33 upon which is applied a force such as the pressure of the starting air, through the medium of a pipe 34 and a valve 35.

When the unit is shut down, and, at all events, before the next starting up period, it must be prepared for the same by bringing the motive pistons back to their outer dead centers.

According to my invention, this may be done in a very -simple manner, without having to empty the intermediate reservoirs, firstly as shown in Figs. 1 and 3, by causing thesuction pressure to act on the rear face of the highpressure pistons such as 2 In the case, in which energy accumulators are located in the interior of the motive pistons, as illustrated in Fig. 3, the diameter Dm of the motive pistons is chosen such as not to differ substantially. The capacities limited by the rear faces of said pistons are -also interconnected during the setting -of the motive pistons for the next starting period, for example through the medium of pipe connections such as 31 and 38, and by the opening of .avalve 34.

Simultaneously, the capacity of the low-pressure compressor may advantageously be emptied, for example by the opening of a valve 26, connected with said compressor by a pipe connection 26 and, in the same manner, .the pressure in the accumulators 6 and ii is also released, for example by opening up a valve 25.

, At least one of the piston assemblies may be displaced by suitable means, for no important pneumatic forces now interfere with the outward of said pistons' For example, as indicated in Fig. 1, recourse may be had to a rod operated by a piston 4| against the action of a spring 42. Said rod 40 may be operated by means of compressed air, for example starting air obtained from reservcir 9 which acts upon piston 4 I, said compressed air being advantageously fed thereto through the same circuit as 34, which controls the piston 33 of the injection pump. Said circuit may afterwards be discharged by the opening-of a valve 28. Under the thrust of the compressed air, the rod 40' forces piston 2 back to its outer. deadcenter. As soon as this has been done, the valve 28 is opened and the rod 40 returned to its initial position under the action of the spring 42.

The regulation of motor-compressor units of the type described isgenerally effected automatically, in the known'manner consisting in proportioning the amount of fuel injected to the demand for compressed air. To this effect, the quantitative regulation control device. associated with the fuel pump, such, for example, as a sliding rod 52, of the type shown in my prior Patcut No.- 2,038,442, for,..instance, is operated by a device acted upon by the variations in the delivery pressure, such, for example, as a piston 53 subjected on one face to the delivery air pressure, and on the other to the thrust of a spring or the action of a manometric cell. Said elements are set so that, up to a given pressure close to the normal operating pressure the amount of fuel injected increases with the pressure; whereas beyond said given pressure, the

fuel feed on the contrary decreases as the delivery pressure increases.

In motor-compressor units of the type described above which comprise no braking forces or air delivery during the starting up period,

function of the variation in the lower stage pressure, for example as shown in Fig. 1, by causing said pressure to act on a piston such as 53 operating for example, through the medium of a cam on the rod 52 adapted. to effect the quantitative regulation of the fuel injection. In this manner the injection of overdoses of fuel when the resistance on the compressor end is reduced it is safer to regulate the fuel injection as a.

is avoided. In normal operation, the high and low stage pressures vary proportionally.

The action of the high and low stage pressures may also be combined to regulate the fuel injection.

The operation of all the valves mentioned hereabove may advantageously be effected by a single control device, which in its different positions controls the starting up operations, the transitory or warming up period, the normal operation, and the shut down.

For example, as shown in Fig. 1, valves 23, 24, 25 and 26 may be operated by means of cams suitably distributed on a common shaft 45, theangular. displacement of which is effected by means of a crank 46. I

Valves l5 and 28 may be disposed opposite one another, and their operating rods I5 and 28 may be set so as to be operated by an extension of the crank arm 46, in sucha manner that, for each of the characteristic positions of said crank, one of said valves will'be open and the other closed. i

The valves II and 35 may be operated through the medium of the same oscillating member 41,

the latter being subjected to angular displacements by the extension of crank arm 46.

Said crank arm 46 might, for example, occupy for the shut down the position I, and when moved to position II which is an intermediate position,

which in turn starts'up the unit by opening up valves 8 and 8 a When moved to the position II, the valve 23 is still closed; but in passing from positions 11 to III, which is that of normal operation, valve 23 is opened and connects the accumulators 6 and .6 with the delivery of the high-pressure stage; and said valve 23 remains open continuously in normal operation;

In the above manmuvre, the valves 24, 25 and 26 are closed by the rotation of shaft 45.

. In normal operation, crank arm 46remains in position 111. .To shutdown the unit, said crank arm is swung back into position I, which move has the following effect.

. 1. By the tilting of the oscillating member 41 i 'the 'valve 35 is opened, which stopsthe fuel injector by the action of the starting air on piston 33, and rod 40 is driven outwards by the air pressure acting on piston 4|, thus setting the pistons on their outer dead centers;

2. The valve 24 is opened, thus releasing the pressure in the high-pressure compressor; the valves 25 and 26 are also opened, the first for the release-of the pressure in the accumulators 6 and 6 and the second for releasing the pressure in the low-pressure compressor;

3. The valve 23 is closed, cutting ofi" the communication between the delivery of the highpressure compressor and the accumulators E and 5 At the end of the course of crank arm 46 (position I) the valve 28 is opened by crank arm 46, the rod 40 is released and returned to its initial position by the spring 42, and the plunger 32 of the fuel injection pump 3| is also released. The unit is then ready to be started up again.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications thereto will occur to a person skilled in the art.

What I claim is:

1. In a free piston internal combustion engine compressor, having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, and means mechanically connected to and actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal pressure during the transition period to normal operation.

2. In an internal combustion engine compressor according to claim 1, said last means including an auxiliary compressor for gradually withdrawing a part of the starting air from the accumulator and a driving linkage connecting said compressor and said free piston. I

3. In an internal combustion engine compressor according to claim 1, said last means including a compressor for withdrawing a portion of the starting air from the accumulator and for delivering the withdrawn starting air into a container for the starting air, and a driving linkage connecting said compressor and said free piston.

4. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal pressure during the transition period to normal operation, said last means including a valve for releasing a part of the starting air from the accumulator and means for automatically opening said valve, said opening means being operated by said free piston when the latter passes beyond its normal inner dead-point position under the influence of 'too great a return energy.

5. In a free piston internal combustion engine compressor having at least one accumulator chamber which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, the accumulator comprising two partial chambers, means to introduce compressed air into the outer partial chamber, and a valve connecting said chambers, whereby by the opening of said valve starting is eifected.

6. In an internal combustion ezigine compressor according to claim 5, means to open said valve comprising a piston connected to the valve and located in the outer partial chamber, and 2.

return stroke valve opening into the said outer partial chamber, whereby the pressure prevailing in the outer partial chamber opens the first valve after a release of the pressure has occurred on the outside of the said piston.

'7. In an internal combustion engine compressor according to claim 5, a spring urging the valve to closed position, said spring being of such strength that the valve remains open as soon as starting has been effected.

8. In an internal combustion engine compressor according to claim 5, a hollow stationary piston projecting into the interior of the hollow free piston, the interior of the stationary piston forming the outer partial chamber of the accumulator, and the interior of said free piston forming the inner partial chamber of the accumulator.

9. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal pressure during the transition period to normal operation, a high pressure pipe, a connecting pipe between the interior of the accumulator which serves for-the stabilization'and the high pressure pipe, a valve controllable from the outside in said connecting pipe, and a return stroke valve which shuts oil the interior of the accumulator from the high pressure pipe as long as there prevails in the additional compressor cylinder a pressure which is greater than the pressure in the high pressure pipe.

10. In a free piston internal combustion engine. compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to. the normal pressure during the transition period to normal operation, means controlled by the stopping of the injection of fuel to shut down the compressor for bringing the free pistons to their outer dead points.

11. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal pressure during the transition period to normal operation, a piston, a rod connected to said piston and engageable with said free piston, means to conduct starting air to one side of said piston, and a valve in said conducting means, whereby upon opening said valve the rod brings the free piston into its outer dead-point position.

12. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal. pressure during the transition period to normal operation, a piston, a ramrod connected to said piston and engageable with said free piston, means to conduct starting air to one side of said piston, and a valve in said conducting means, whereby upon opening said valve the ramrocl brings the free piston into its outer dead-point position, and a spring normally resisting movement of said piston.

13. In a multi-stage internal combustion engine compressor with opposed free pistons and having an engine cylinder and compressor cylinders asymmetrically arranged at the two sides of the engine cylinder, means to subject the rear side of the compressor piston of the high pressure stage to the substantially constant inlet pressure of this stage.

14. Inan internal combustion engine compressor according to claim 13, a chamber on the rear side of the high pressure a connecting pipe between said chamber and the interior of the high pressure compression cylinder, a valve in said connecting pipe, and means to 1 nected to said member to control all the, valves which serve for the transition to normal operation and for the starting of the engine.

16. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compremed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the mean pressure in this accumulator to the normal pressure during the transition period to normal operation, a single trolled by said controlling member, and means connected to said member to control all the valves which serve for the transition to normal operation and for the starting of. the engine, said member comprising a shaft, a controlling lever fixed on the shaft, a plurality of camson said shaft, and means concams to operate a plurality of valves.

1'7. In a free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator means actuated by said free lowering the meanpressure to the normal pressure durto start the engine, piston for gradually in this accumulator compressor piston,

ing the transition period to normal operation, a single controlling member, and means connected to said member to control all the valves which serve forthe transition to normal operation and for the starting of the engine, said member comprising a shaft, a controlling. lever fixed on the shaft, a plurality of cams on said shaft, and means controlled by said cams to operate a plurality of valves, said controlling lever having an extension cooperating alternately on the one hand with the valve rods of two opposed valves and, on the other hand, with a rocking lever for operating two further valves alternatively.

18. In a multi-stage free piston internal combustion engine compressor having at least one accumulator which serves for stabilizing the engine, means for blowing compressed air into said accumulator to start the engine, means actuated by said free piston for gradually lowering the means pressure in this accumulator to the normal pressure during the transition period to normal operation, said engine having a fuel injection pump, a controlling member for the fuel injection pump, means'to subject said controlling member to the pressure of the compressed gas, a spring acting on said controlling member in opposite direction to the compressed gas, said parts being so constructed that until a gas. pressure is reached substantially corresponding to that of normal operation the fuel injection increases with increasing pressure, while, when this pressure is exceeded, the injection of fuel decreases with further increase of the gas pressure.

19. In a free piston internal combustion engine compressor having at least one pneumatic accumulator which serves for stabilizing the engine,

means for releasing apart of the air under pressure contained in said accumulator,

said means being actuated by said free piston when the latter passes beyond its normal dead-point position under the influence of too great a return energy,

20. In an internal combustion engine compressor with at least one free piston, having at least one accumulator which serves ior stabilizing the engine, the accumulator comprising two coaxial partial chambers, means to introduce compressed air into the outer partial chamber, and a valve connecting said chambers, whereby opening of said valve starting is effected.

21. In a multi-stage internal combustion engine compressor according to claim 13, two pneu-' matic accumulators symmetrically arranged at the two ends of the engine cylinder.

RAUL PATERAS PECARA.

by the 

